A conventional card connector assembly is shown in FIGS. 6A and 6B (see Japanese Patent Application No. 9-22762). In this card connector assembly, two card connectors (first and second card connectors) that receive PCMCIA standard PC cards are stacked.
Here, the card connector assembly 200 shown in FIG. 6A is constructed by vertically stacking two card connectors that receive PC cards C, i.e., a first card connector 201 and a second card connector 210.
The first card connector 201 is constructed by disposing contacts 203 that contact a PC card C in two rows (upper and lower rows) in the upper portion of the housing 202. A ground member 205 that contacts the ground part of the PC card C that is received in the first card connector 201 is formed on the top surface of the housing 202 of the first card connector 201.
Furthermore, the second card connector 210 is constructed by disposing contacts 211 that contact a PC card (not shown) in two rows (upper and lower rows) in the lower portion of the housing 202. A ground member 213 that contacts the ground part of the PC card that is received in the second card connector 210 is formed in the portion of the housing 202 that is lower than the first card connector 201.
The first card connector 201 and second card connector 210 are placed on a common circuit board (not shown in the figure). The contacts 203 and ground member 205 of the first card connector 201 are connected to the circuit board by connection parts 204 of the contacts 203 that extend forward (toward the right in FIG. 6A) from the housing 202, connection parts 206 of the ground member 205, a relay board 207 that is connected to these connection parts 204 and 206, and a relay connector 220 that connects the relay board 207 to the circuit board. Furthermore, the contacts 211 and ground member 213 of the second card connector 210 are connected to the circuit board by connection parts 212 of the contacts 211 that extend forward from the housing 202, connection parts 214 of the ground member 213, a relay board 215 that is connected to these connection parts 212 and 214, and the relay connector 220 that connects the relay board 215 to the circuit board.
Moreover, the card connector assembly 230 shown in FIG. 6B is a modified example of the card connector assembly 200 shown in FIG. 6A, and is constructed by vertically stacking two card connectors (a first card connector 231 and a second card connector 240) that receive PC cards C.
The first card connector 231 is constructed by disposing contacts 233 that contact a PC card C in two rows (upper and lower rows) in the upper portion of the housing 232. A ground member 235 that contacts the ground part of the PC card C that is received in the first card connector 231 is formed on the top surface of the housing 232 of the first card connector 231. Furthermore, the second card connector 240 is constructed by disposing contacts 241 that contact a PC card (not shown) in two rows (upper and lower rows) in the lower portion of the housing 232. A ground member 243 that contacts the ground part of the PC card that is received in the second card connector 240 is formed in the portion of the housing 232 that is lower than the first card connector 231.
The first card connector 231 and second card connector 240 are placed on a common circuit board (not shown in the figure). The contacts 233 and ground member 235 of the first card connector 231, and the contacts 241 and ground member 243 of the second card connector 240, are connected to the circuit board by connection parts 234, 236, 242 and 244 that extend from the housing 232, a single relay board 237 that is connected to these connection parts 234, 236, 242 and 244, and a relay connector 250 that connects the relay board 237 to the circuit board.
Furthermore, the card connector assembly shown in FIG. 7 (see Japanese Patent Application No. 8-264240), for example, is another example of a card connector assembly in which two card connectors (first and second card connectors) that receive PCMCIA standard PC cards are stacked.
The card connector assembly 300 shown in FIG. 7 is constructed by vertically stacking two card connectors (a first card connector 301 and a second card connector 310) that receive PC cards (not shown in the figure).
In the first card connector 301, contacts that contact a PC card are provided in two rows (upper and lower rows) on the front wall surface (right wall surface in FIG. 7) of a housing 302, and connection parts 303 of the contacts are formed to protrude forward from this front wall surface. A ground member that contacts the ground part of the PC card received in the first card connector 301 is provided in the upper portion of the front wall surface of the housing 302 of the first card connector 301, and connection parts 304 of the ground member are formed to protrude forward from this front wall surface. Furthermore, in the second card connector 310, contacts that contact a PC card are provided in two rows (upper and lower rows) on the front wall surface (right wall surface in FIG. 7) of a housing 311, and connection parts 312 of the contacts are formed to protrude forward from this front wall surface. A ground member that contacts the ground part of the PC card received in the second card connector 310 is provided in the upper portion of the front wall surface of the housing 311 of the second card connector 310, and connection parts 313 of the ground member are formed to protrude forward from this front wall surface.
The first card connector 301 and second card connector 310 are placed on a common circuit board 330. The contacts and ground member of the first card connector 301, and the contacts and ground member of the second card connector 310, are connected to the circuit board 330 by the connection parts 303, 304, 312 and 313 that extend from the respective front wall surfaces of the housings 302 and 311, a flexible circuit board (hereafter referred to simply as “FPC”) 305 that is connected to these connection parts 303, 304, 312 and 313, and a relay connector 320 that connects the FPC 305 to the circuit board 330.
Meanwhile, as a result of the spread of portable-type personal computers in recent years, there has been an increasing demand not only for such card connector assemblies that receive PCMCIA standard PC cards, but also for a card connector assembly comprising a first card connector and a second card connector that are stacked for the connection with two cards such as memory cards that have mutually different transmission speeds. An example is a card connector assembly comprising a connector that is connected to a memory card with a relatively high transmission speed (approximately 3 GHz) as the first card connector, and a connector that is connected to a PCMCIA standard PC card with a relatively low transmission speed as the second card connector.
When an attempt is made to use the card connector assemblies 200 and 230 shown in FIGS. 6A and 6B or the card connector assembly 300 shown in FIG. 7 to connect with cards having mutually different transmission speeds, the following problems have been encountered.
Specifically, in the case of the card connector assembly 200 shown in FIG. 6A, the signal transmission path between the first card connector 201 and the relay connector 220 is constructed from the connection parts 204 of the two rows (upper and lower rows) of the contacts 203, and the relay board 207 that is connected to these connection parts 204. Furthermore, the signal transmission path between the second card connector 210 and the relay connector 220 is constructed from the connection parts 212 of the two rows (upper and lower rows) of the contacts 211, and the relay board 215 that is connected to these connection parts 212. In these signal transmission paths, since the connection parts 204 of the contacts 203 and the connection parts 212 of the contacts 211 are each formed in two rows (upper and lower rows), in cases where a memory card having a relatively high transmission speed of approximately 3 GHz is connected to one of the connectors 201 and 210, noise is produced between the connection parts 204 of the two rows (upper and lower rows) or between the connection parts 212 of the two rows (upper and lower rows), so that such a card connector assembly is not suitable for high-speed transmission. Moreover, since the connection between the connection parts 204 of the contacts 203 and the relay board 207, and the connection between the connection parts 212 of the contacts 211 and the relay board 215, are accomplished via through-holes, the energy consumption of transmission signals in the connection parts via through-holes is large, so that noise tends to be introduced. Thus, such a card connector assembly is not suitable for high-speed transmission for this reason as well.
Furthermore, in the card connector assembly 230 shown in FIG. 6B as well, since the connection parts 234 of the contacts 233 and the connection parts 242 of the contacts 241 are similarly each formed in two rows (upper and lower rows) in the signal transmission paths, in cases where a memory card having a high transmission speed of approximately 3 GHz is connected to one of the connectors 231 and 240, noise is introduced between the connection parts 234 of the two rows (upper and lower rows) or between the connection parts 242 of the two rows (upper and lower rows), so that such a card connector assembly is not suitable for high-speed transmission. Moreover, since the connection between the connection parts 234 of the contacts 233 and the relay board 237, and the connection between the connection parts 242 of the contacts 241 and the relay board 237, are also accomplished via through-holes, the energy consumption of transmission signals in the connection parts via through-holes is large, so that such a card connector assembly is not suitable for high-speed transmission.
Meanwhile, in the card connector assembly 300 shown in FIG. 7, the signal transmission paths between the first and second card connectors 301 and 310 and the relay connector 320 are constructed from the connection parts 303 and 312 of the two rows (upper and lower rows) each, and the FPC 305 that is connected to these connection parts 303 and 312. In these signal transmission paths, the connection parts 303 and 312 are each formed in two rows (upper and lower rows), but the length of these parts is relatively short, while the FPC 305 is relatively long; accordingly, in cases where a memory card having a high transmission speed of approximately 3 GHz is connected to one of the connectors 301 and 310, noise introduced between the connection parts 303 of the two rows (upper and lower rows) or between the connection parts 312 of the two rows (upper and lower rows) is small, so that this card connector assembly can be used for high-speed transmission as well. However, there is a problem in that a relatively long FPC 305 is needed, so that the cost of the product becomes high. Moreover, since the connection between the connection parts 303 and 312 and the FPC 305 is accomplished via through-holes, the energy consumption of transmission signals in the connection parts via through-holes is large, so that the transmission characteristics are somewhat inferior even with the use of the FPC 305.